Can they be interchanges with each other atall,I've bought a s2 and the ecu has got heart,triangle,# on the sticker but I've been offered a chipped ecu but it's got a different code on it

 

aslong as the ecu u have been offered is a blue red black ecu 1988 cars then all will be fine

if its a blue red blue (s1) 84/85
or a blue red white (early s2) 86/87

then no as these will not sense the knock sensor as may cause running issues

the hearts diamond hash ecu came on 89/90 cars

 

Would it not be possible to run an early ecu with the knock sensor unplugged so it doesn't get a reading

 

mines like that, blue red white iirc, knock sensor unplugged

Its all gonna be un plugged very soon, efi is happening